Currently, the 3GPP (Third Generation Partnership Project) has proceeded with the standardization of LTE-advanced (hereinafter, specifications of LTE Release 10 and subsequent specifications are collectively called “LTE-A”) that is an evolved radio interface of LTE (Long Term Evolution) Release 8/9 specifications (hereinafter, referred to as LTE or Rel-8/9). LTE-A is aimed at actualizing higher system performance than LTE while keeping backward compatibility with LTE.
In LTE-A, having backward compatibility with LTE is one of requirements, and adopted is a transmission band having a plurality of base frequency blocks (hereinafter, referred to as component carriers (CCs)) each having a bandwidth usable in LTE. It is called carrier aggregation (for example, Non-patent literature 1) transmitting signals at the same time thus using a plurality of component carriers.
In LTE-A, a micro-cell (for example, pico-cell, femto-cell, relay cell, etc.) having a local coverage area with a radius of about several tens of meters is formed in a macro-cell having a wide-range coverage area with a radius of about several kilometers. Such a network configuration in which nodes with different power are overlaid is called HetNet (Heterogeneous Network). A radio base station forming the macro-cell is called the macro-base station, and a radio base station (pico-base station, femto-base station, relay base station, etc.) forming the micro-cell is called the micro-base station.